Document Type : Original Article
Authors
1
Pharmacognosy Department, Pharmaceutical and Drug Industries Research Division, National Research Centre
2
Center of Scientific Excellence for Influenza Viruses,department of water pollution research division of environmental research and climate change. National Research Centre, El-Buhouth Street, Dokki, Cairo, 12622, Egypt 3Department
3
Center of Scientific Excellence for Influenza Viruses, National Research Centre, El-Buhouth Street, Dokki, Cairo, 12622, Egypt
4
Pharmacognosy Dept. , National Research Centre; 33-Elbohouth St, (Former El-Tahrir St.), Dokki – Giza-Egypt. P.O.12622, ID: 60014618
Abstract
Background: Ligustrum genus is part of the Oleaceae family it is commonly utilized as attractive trees or hedges in parks and gardens; it was most commonly seen in urban areas. Ligustrum species were broadly used in folkloric medicine. In China the plant was utilized to treat many illnesses, as rheumatic pains, cloudy vision, tinnitus, backache, sleeplessness, palpitations, and menopausal issues. Additionally, it was used to relieve symptoms associated with aging & as anticancer, antidiabetic, and hepatoprotective. Ligustrum ovalifolium (LO) Hassk was widely distributed in East Asia and is usually cultivated as an ornamental plant in many other countries. Methodology: The dried aerial non flowering parts of LO were extracted with MeOH (crude extract), part of crude extract was fractionated by liquid /liquid extraction with ethyl acetate (EtOAc) followed by n-butanol (n-BuOH), then the dried EtOAc fraction is partitioned between n-hexane and 90% methanol to obtain five different fractions which were in vitro screened against SARS-CoV-2. Results: All extract fractions had high safety on Vero-E6 cells and exhibited activity against SARS-CoV-2. The highest activity was attributed to the 90% methanol fraction with (IC50) = 7.895 µg/ml and safety index (SI) = CC50/IC50 = 5851/7.895 = 741.1. Analysis of the active fraction (90% methanol) using LC-MS/MS resulting in the detection of 77 metabolites in negative ionization modes. They were arranged according to their abundant as: iridoid, phenylethanoid and phenylpropanoid compounds, triterpenoids, lignans, flavonoids, phenolic acids, long chain fatty acids and coumarin. Molecular docking study was used to investigate the binding affinity of the detected compounds against SARS Cov-2 main protease (MPro) and spike protein (S). It was found that acteoside (25), (2``R)-10-hydroxy-2``-methoxyoleuropeins (31), ligustaloside A (34) and rutin (19) exhibited outstanding binding affinities toward the active site of MPro and achieved docking scores of -13.58, -11.93, -11.92 and -11.22 kcal/mol, respectively. On the other hand, the best binding affinities against receptor binding domain (RBD) of SARS Cov-2 spike protein were exhibited by ligupurpuroside A (33), isoacteoside (29), ibotalactone B (14) and acteoside (25) they have achieved docking scores of -10.16, -8.97, -8.43 and -7.97 kcal/mol respectively. Conclusion: L. ovalifolium Hassk 90% methanol fraction enriched with valuable compounds as iridoids, phenylethanoid/propanoids & triterpenoid derivatives of oleanolic acid & ursolic acid these compounds were responsible for the antiviral activity against SARS-Cov2. This is the first study done on L. ovalifolium Hassk aerial parts which revealed the detection compounds via LC/MS/MS, Additionally, the screening of the in vitro & in silico antiviral activity against SARS CoV-2 were first evaluated in this study.
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